Just need to form a few people authority and makes the change, it's not difficult. The problem is that each has his own ego and interest, and it definitely hinders the development and usage of the bitcoin.

whether our technological level has reached the point where we can do it now without sacrificing current security. Obviously, 10 years from now, a 2-4 MB blocksize hardfork is extremely doable and should preserve the current security

As someone who "supports" segwit on it's merits, and a 2Mb block increase for compromise, I have yet to see any compelling argument for this. Can someone point me to something I can read and digest that would actually accomplish that plus something that refutes that. I'm not talking about things that are filled with propaganda and ideology but solid arguments based on technical issues and facts etc.

But as "guardians of the protocol", their power is zilch, and hence as "decentralizing power element" their influence is zilch.

I've read a lot of your posts on this and you've failed to convince me except in the case where 100% of the miners are in agreement and in opposition to a very large majority of those running full nodes.

If, for example, 75% (hash) of the miners decide to change something radical about the protocol, the full nodes can choose to reject their blocks while accepting those from 25% of the miners. Yes, the entire system is disrupted for some period of time but it was going to be anyway.

I agree with you, but in that case, it are STILL NOT the full nodes that decide one way or another, but the users in the market *with their money*, not with their nodes. If the users sell in majority the coins on the 75% chain, and buy the coins on the 25% chain (remember that from the start, all users have equal amounts of both), what will happen ?

A) the exchanges listing both coins will make a lot of money on the transactions (so, yes, they will list both coins).

B) users will NEED TO TRANSACT on both chains. So if all nodes block one chain, they will find a way to connect directly to the miner nodes, and exchanges (see A) will do so too.

C) in the end, coins on the user-preferred chain will be worth much more than those on the user-rejected chain (offer and demand in the exchange happening in A).

D) miners will adapt their hash rate to the most profitable chain, until this finds an equilibrium: it will find an equilibrium when hash rates agree with market price. As long as an expensive chain has little hash rate, it becomes interesting for miners to start mining that chain, the forkers on the 25% chain will make a lot of money ; a cheap chain with a lot of hash rate (and difficulty) will not be advantageous to mine, the 75% miners will be mining at loss. So miners will follow market price.

That's exactly what happened with the ETH/ETC split (ok, the miners didn't initially go in majority to the small chain, true)And whatever was the ratio of full nodes doesn't matter in this. Users voting in the market determined all.

Now, in bitcoin, there's an extra difficulty, which is the very slow difficulty adjustment rule. Unless that is adapted in the fork too (could be), any split will bring initially the "low miner count" chain in difficulties, because they will only be able to mine a few blocks. But also the majority chain will slow down. This is what keeps unity between miners, and which wasn't the case on ethereum.

whether our technological level has reached the point where we can do it now without sacrificing current security. Obviously, 10 years from now, a 2-4 MB blocksize hardfork is extremely doable and should preserve the current security

As someone who "supports" segwit on it's merits, and a 2Mb block increase for compromise, I have yet to see any compelling argument for this. Can someone point me to something I can read and digest that would actually accomplish that plus something that refutes that. I'm not talking about things that are filled with propaganda and ideology but solid arguments based on technical issues and facts etc.

But as "guardians of the protocol", their power is zilch, and hence as "decentralizing power element" their influence is zilch.

I've read a lot of your posts on this and you've failed to convince me except in the case where 100% of the miners are in agreement and in opposition to a very large majority of those running full nodes.

If, for example, 75% (hash) of the miners decide to change something radical about the protocol, the full nodes can choose to reject their blocks while accepting those from 25% of the miners. Yes, the entire system is disrupted for some period of time but it was going to be anyway.

I agree with you, but in that case, it are STILL NOT the full nodes that decide one way or another, but the users in the market *with their money*, not with their nodes.

Right, but I never said full nodes are the only ones that decide one way or another, you're saying that and then saying the conclusion is that they thus have zero power. You've simply failed to convince me that full nodes have zero power. It's more like a 3 tier system. Everything is fine as long as everyone agrees with what the miners are doing. If they don't, it's bumped up to the full nodes and from there it can continue up to the final level of users. At the end of the day, it's a combination of all 3 that will finally settle on some sort of resolution.

Just need to form a few people authority and makes the change, it's not difficult. The problem is that each has his own ego and interest, and it definitely hinders the development and usage of the bitcoin.

They have self and selfish thoughts, they never think for everyone. Bitcoin is in trouble, and it needs resolution. Hardfork is very necessary.

whether our technological level has reached the point where we can do it now without sacrificing current security. Obviously, 10 years from now, a 2-4 MB blocksize hardfork is extremely doable and should preserve the current security

As someone who "supports" segwit on it's merits, and a 2Mb block increase for compromise, I have yet to see any compelling argument for this. Can someone point me to something I can read and digest that would actually accomplish that plus something that refutes that. I'm not talking about things that are filled with propaganda and ideology but solid arguments based on technical issues and facts etc.

But as "guardians of the protocol", their power is zilch, and hence as "decentralizing power element" their influence is zilch.

I've read a lot of your posts on this and you've failed to convince me except in the case where 100% of the miners are in agreement and in opposition to a very large majority of those running full nodes.

If, for example, 75% (hash) of the miners decide to change something radical about the protocol, the full nodes can choose to reject their blocks while accepting those from 25% of the miners. Yes, the entire system is disrupted for some period of time but it was going to be anyway.

I agree with you, but in that case, it are STILL NOT the full nodes that decide one way or another, but the users in the market *with their money*, not with their nodes.

Right, but I never said full nodes are the only ones that decide one way or another, you're saying that and then saying the conclusion is that they thus have zero power. You've simply failed to convince me that full nodes have zero power.

Then I don't know how to convince you. How could one establish the proof that entities X have no power of decision on outcome U ? I would think that if one proves that if outcome U is largely independent of whatever X does, the proof is established, no ?

Of course, we cannot do real experiments, but Gedanken experiments are good enough if we take into account all logical possibilities, and eliminate only those that can be agreed upon to be highly improbable. That's an accepted practice in many fields of study.

As such, I think I established that even in the extreme case where ALL non-mining nodes disagree with a miner protocol, that miner protocol can nevertheless be the actual one on the block chain. You already agreed with me that this was true when all miners (like they are used to do) have a common protocol and didn't deviate from it. In that case, there's only one block chain out there, and full nodes can accept it, or can stop. But they cannot FORCE miners to accept THEIR version of the protocol.

You raised the case when miners were not united, but a fraction went with the full nodes' protocol preference. I just demonstrated that if the miners disagreed, then we have a hard fork, and there are now TWO CHAINS out there. So in general, some full nodes will download chain A, and others will download chain B. The most extreme case, is where all full nodes refuse one of both (say, refuse A), and ONLY download B. I demonstrated that even in that extreme case, under reasonable assumptions of behaviour of exchanges and users, the relative values of both chains, with the eventuality of one actually going to zero, is entirely determined by what the market will do in this case, and AGAIN, the full nodes refusing chain A can very well result in chain A being the dominant one, if ever the market decides so. So in the case you raised, too, whatever the full nodes tried to impose, has no effect on the outcome.

If that is not a sufficient proof that whatever full nodes do, they have no *decision power over the protocol* I don't know what could convince you.

Now, I will agree with you that they have some "psychological power before the split". It may be a vague indication of what users MIGHT do if ever they were given a choice in the market. But even that is very limited: full nodes are not representative of the market. They do not faithfully represent the stake owners, and they do not faithfully represent the traders. They, especially, do not represent newcomers to bitcoin that will also vote in the market. So their indicative power of what the market might do, is not necessarily of much value either. It is only in the case where miners are very hesitant to fork off, and are too incompetent/lazy... to do a serious market study, that they might take full node preferences for a market study to base their decision to fork or not, on.

In any case, bitcoin is constructed such, that "forking away" is risky for miners, because of the slow difficulty adjustment. Miners need to know that they will fork off with big majority before attempting to do so. So, if full nodes can influence anything, they may *increase the pressure on miners NOT to fork away*. If ever full nodes in majority keep the old protocol, miners might take this as an indication that, if ever they fork away, the market will not support their initiative, and it will even be harder for them to fork away.But at no point, full nodes could IMPOSE a CHANGE upon miners, if miners are not convinced that they will fork away with large majority of their peers, because in as much that full nodes are an indication of what the market would do (even though, as I said, this is highly doubtful because they are not representative), they STILL face the difficulty adjustment question.

edit: I would like to point out that I am not trying to do any politics here. I simply see some claim that "to stop the Russians, we should all have plastic guns" and that a whole argument of how it is important to keep the number of plastic guns high, and how some measures cannot be taken because the number of plastic guns goes down. Just by logic, my point is "plastic guns won't stop the Russians", and I try to argue all cases where plastic guns would be used to try to stop the Russians, and obviously fail if you think about it: if ever they are stopped, or not, it doesn't depend on holding plastic guns.So I'm putting into question the argument that plastic guns are important, because it sounds obviously false to me. That's all. After I've listed several arguments, someone tells me "you've still not convinced me that plastic guns won't stop the Russians at all. Of course, with ONLY plastic guns, we won't get there. But I think they still play a role in stopping Russians".

whether our technological level has reached the point where we can do it now without sacrificing current security. Obviously, 10 years from now, a 2-4 MB blocksize hardfork is extremely doable and should preserve the current security

As someone who "supports" segwit on it's merits, and a 2Mb block increase for compromise, I have yet to see any compelling argument for this. Can someone point me to something I can read and digest that would actually accomplish that plus something that refutes that. I'm not talking about things that are filled with propaganda and ideology but solid arguments based on technical issues and facts etc.

But as "guardians of the protocol", their power is zilch, and hence as "decentralizing power element" their influence is zilch.

I've read a lot of your posts on this and you've failed to convince me except in the case where 100% of the miners are in agreement and in opposition to a very large majority of those running full nodes.

If, for example, 75% (hash) of the miners decide to change something radical about the protocol, the full nodes can choose to reject their blocks while accepting those from 25% of the miners. Yes, the entire system is disrupted for some period of time but it was going to be anyway.

I agree with you, but in that case, it are STILL NOT the full nodes that decide one way or another, but the users in the market *with their money*, not with their nodes.

Right, but I never said full nodes are the only ones that decide one way or another, you're saying that and then saying the conclusion is that they thus have zero power. You've simply failed to convince me that full nodes have zero power.

Then I don't know how to convince you. How could one establish the proof that entities X have no power of decision on outcome U ? I would think that if one proves that if outcome U is largely independent of whatever X does, the proof is established, no ?

So one of the problems I have with your "logic", is that half of the time you come up with these 1 + 1 equal 2 equations that ignores some other factor or is based on multiple assumptions, some of which can be flawed.

Outcome U is only accomplished because X "put" the decision into the hands of Y. So if ultimately you believe that the ability to do that still does not mean they have any power what so ever, then that's where we will never agree no matter what sort of "logic' you try and throw at it.

I also find your statement that full nodes are not representative of the market truly perplexing. While we don't know the entire makeup, it's clear that a good portion of those full nodes are exchanges, payment processors, companies, traders and users. So how one then can possibly say that they're not representative of the market is just.. well I can't think of a good word for it.

I suspect what this comes down to is, if you are predisposed to believe (or want it to be true) that full nodes have no power, then all they can do is "influence" through action as you believe. But others believe that the ability to perform an action that "influences" things the way you want is, ultimately, power.

As for your plastics guns analogy. When you throw things like that out there I end up questioning your sincerity. You take some non applicable analogy and then basically imply that anyone that thinks this is true is not logical. i.e. implying they're "crazy". Throwing in the "I'm not being political" prior to that further makes it appear that you're not sincere and are just trying to advance some agenda.

Anyway. I think it's safe to say that neither of us will be able to convince each other one way or the other.

I cannot be forced by any amount of miners to accept an invalid chain. They cannot spend coins they don't own. The ONLY power they have is to NOT include valid txns. That's a pretty powerful toy I have (a full node).

If 'most' of the miners jump on to a different spec, say BU, Me and my full node can choose not to, and the remaining miners including MYSELF, can keep our chain running. I'll start mining if need be (and if I can make some money). Without TRUSTING ANYONE.

The minute I HAVE to jump ship, because I am not running a full node, so cannot determine for myself what chain to run, BTC is dead.

Yes - Miners make the chain, but any chain requires miners, and Bitcoin has excellent self regulation built in!

If miners leave I can join. If miners join, inefficient miners leave. if Txn/s is too high and blocks are full, the fee's go up. if TXN/s too low, the fees come down. ALL OF THIS self regulated by market forces.

Running a full node, means you are FREE to do what you want. When the time comes, you may need to mine. You may not.

But this is only possible - IF you run a full node.

Otherwise, if BTC becomes JUST FOR BIG FAT MINERS - It's no better than a Chinese version of VISA. Only much slower, inefficient and more expensive.. Then I have ZERO power AND I need to TRUST the miners (since I can't leave..).. No thanks.

So one of the problems I have with your "logic", is that half of the time you come up with these 1 + 1 equal 2 equations that ignores some other factor or is based on multiple assumptions, some of which can be flawed.

Well, I invite you to point them out.

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Outcome U is only accomplished because X "put" the decision into the hands of Y.

Nobody "put power" in the hands of anyone. This is a dynamical system, with its different behavioural laws. Like in nature, nobody "put the power of decision in the hands of this or that species". Or like the solar system: the laws of gravity tell the planets how to move. Nobody "gave the sun the power to decide where the planets go". When you study the system, you try to find the different behaviours of the components as a function of the behaviour of the other components in the system. Once you understand that, you can try to predict how any change in behaviour of one component, influences the behaviour of another component. That's all.

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I also find your statement that full nodes are not representative of the market truly perplexing. While we don't know the entire makeup, it's clear that a good portion of those full nodes are exchanges, payment processors, companies, traders and users. So how one then can possibly say that they're not representative of the market is just.. well I can't think of a good word for it.

Well, there are more than a million of bitcoin users. There are about 7000 full nodes. Clearly they are not representative. As one can start up as many nodes as one wishes, and as this is totally not related to what one does on the market, it must be rather clear that there is no causal link between what happens on the market, and what nodes are running what, no ?Take exchanges. I think we can agree that exchanges will see a mega profit if ever bitcoin splits in a hard fork, because many users are going to trade one of their coin copies, for the other. So even if an exchange is now only running a node that goes with, say, "fork A", of course they will quickly fire up a node that goes with fork B to be able to have their customers trade both of them (and have them reap in the fees on all of these trades). So a big exchange having a node that only runs protocol pre-cursor A, doesn't mean, at all, that they won't start another node for fork B.

As to users, suppose there is a hard fork by miners (that was YOUR proposal). Do you really think that if you are a whale, and you have, say, 100 000 BTC, and after the split, you have now 100 000 BTC-A and of course also 100 000 BTC-B, that you will *refuse the value of your BTC-B holdings* by refusing to transact on chain B ? Do you think people will "throw away free money" because they are now running a node with only one software flavour ?

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I suspect what this comes down to is, if you are predisposed to believe (or want it to be true) that full nodes have no power, then all they can do is "influence" through action as you believe. But others believe that the ability to perform an action that "influences" things the way you want is, ultimately, power.

But this is a purely technical question, which has a reasoned answer, it is not a matter of belief. My "belief" comes from argued thinking about what happens or what is likely to happen in different scenarios, not from any predisposition to anything. I'm trying to understand how this system works in reality, what components have influence on what, and for that, I suppose that these components change their behaviour, and I try to find out what are the propagated consequences of this change in behaviour. That's how you find out how something works.

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As for your plastics guns analogy. When you throw things like that out there I end up questioning your sincerity. You take some non applicable analogy and then basically imply that anyone that thinks this is true is not logical. i.e. implying they're "crazy". Throwing in the "I'm not being political" prior to that further makes it appear that you're not sincere and are just trying to advance some agenda.

These discussions always end up like that: no logical argument. (*) I wonder if in bitcoin land, someone actually thinks logically. As I told you, I saw a claim that seemed to go against how the bitcoin dynamics was established: proof of work was established to avoid any Sybil attack by nodes. As such, anything that doesn't do proof of work was designed not to have any influence on the system. But of course, it is not because it was DESIGNED that way, that it WORKS that way. So, even though bitcoin's design was such that non-mining full nodes were not to have any influence, it could still be the case that they DID have, in practice, some influence. But when analysing on how they could enforce anything, it seems that the design of the bitcoin system was correct: non-mining nodes, do, indeed, have no influence.

So it is quite strange that the argument to the opposite is even used. Bitcoin was explicitly designed NOT to let any influence to full nodes, and moreover, if you think about it, and try to find out if, nevertheless, they COULD have some influence, you find out that all arguments point out that, no, they don't, as was expected (but not proved initially) from the design.

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Anyway. I think it's safe to say that neither of us will be able to convince each other one way or the other.

You can perfectly well convince me with a logical argument: you describe a situation where the full nodes enforce their protocol upon the block chain - which is after all the claim that you believe. If every step in your argument is correct and plausible, then I'm convinced, because then, the confrontation of your arguments with mine will show where one of us is wrong. That's how science is done, usually.

(*) edit: the "plastic gun analogy" was of course not a logical argument. It was an illustration of how I saw the situation. The plastic gun analogy didn't prove anything, the real proof was earlier. Once it was established by logical reasoning that there's no significant way in which full nodes can enforce their protocol, it makes them look like plastic guns. But not before of course. Analogies are not logical arguments, and it wasn't used as such in this case. They are just illustrative, after the logical argument has been given.

Yes, this I give you. I never denied this. A full node INFORMS ITS OWNER. But that is not the claim. If you are informed that the sole block chain out there is not to be trusted according to your node, what do you do now ?

If 'most' of the miners jump on to a different spec, say BU, Me and my full node can choose not to, and the remaining miners including MYSELF, can keep our chain running. I'll start mining if need be (and if I can make some money). Without TRUSTING ANYONE.

Then, by definition, you are not a non-mining full node any more ! You joined the miners, and you are now using your hash power to fork. I hope you are not on your own, because otherwise, your chain is going to grow slowly, and you will probably get nowhere. So the only reasonable case we are discussing here, is when there is already a split between the miners and in fact, what you are doing, doesn't matter much.If you do so, there's a hard fork, and we're now in the case I replied to before, two coins will appear on the exchanges, and users will vote with their money, and miners will follow. In all of this, NON-MINING full nodes didn't play a role. And hey, you WILL also transact on the OTHER chain, because you have coins there, and you will want to dump them.

In the end, whether you were running your full node or not, doesn't change anything: the users in the market will determine the relative market caps and hence, the relative hash rates on both chains. That's my whole point.

It is, in other words, NOT because you were running a non-mining full node that you influenced what so ever in this split. It is because you started mining, or because you sold in the market. The only thing that happened, was that your full node informed you at a certain point, that the chain you expected to see, disappeared. In the case of a split, you wouldn't even know: your full node would just crunch on the chain that is in agreement, and neglect the other one. You wouldn't even know that there was a split.

So let me re-iterate in what I hope is the simplest way I can. Your statement is that full nodes have zero power, "zilch" so they might as well "all" be shut off. The "full nodes have zero power" is what I'm talking about, not your statements where you start to add qualifiers. You have failed to convince me that it's true.

Let's just use an example where 75% of miners want to increase the emissions back up to a starting point of 50 coins/block.

The market won't like that but they have no ability to reject that protocol change. They might drive the price into the tank for awhile, but they've proven time and again that as long as they see they can continue to make money, they'll do so and so will end up just accepting it.

Full-nodes however, can reject those blocks, accept the 25% and bring about a split in the network etc. Now the market has the ability to ultimately make the final decision. Yes, there will be chaos and the outcome would be unknown, but now it's in their hands.

Dino - I know it must seem like we are just dancing around in circles.. .. And I am sorry for that.. BUT.. I have to disagree with you.

A network of FULL nodes can maintain a fully working blockchain, some will mine some won't, that others can join.. it is self determinate and complete. An SPV network can't and isn't.

Uh, of course full nodes are needed. But only mining ones are strictly needed, because they are the ones that make the block chain, the others don't, and hence they are the sole primary SOURCE of data - there isn't any other one. What doesn't make the block chain, cannot influence it. All decisions in a crypto currency are acted into the block chain, and that block chain is the only thing that represents that crypto currency, nothing else (for instance, not the communications protocol), because the block chain is the only cryptographic element in the system. So all decisions are acted in the block chain. If you can't write a piece of data in that block chain, you have no technical decision power.

As a user, you can ask those people that write the block chain, to put something in there for you (one of your transactions). That's how you are a *customer* of those that make the block chain. As a user, you may want to spend good money to induce others to put something in there (one of their transactions to you). As such, you have economical decision power, like any customer has. In order to exercise your economical power, you need to be able to READ (parts of the) block chain. So you need read access ; however, the block chain's cryptographic nature is that you can entirely verify the economic acts that concern YOU by only obtaining a small part of the data (SPV). In fact, the only thing you need to verify is whether transactions in your favour are correctly notified in the block chain, so that you can know that you can transact them yourself later. There must be hence some few accessible places where you can obtain those data, but as these data cannot be cryptographically faked, and as the only place they can come from, are active miners, these active miners are the sole primary source of these data. Whether you access a copy of a copy of these data, or you access them directly from the source, doesn't matter, it doesn't increase the "security" of the system at all from being able to read a copy, if you can have the original.

So let me re-iterate in what I hope is the simplest way I can. Your statement is that full nodes have zero power, "zilch" so they might as well "all" be shut off. The "full nodes have zero power" is what I'm talking about, not your statements where you start to add qualifiers. You have failed to convince me that it's true.

Let's just use an example where 75% of miners want to increase the emissions back up to a starting point of 50 coins/block.

The market won't like that but they have no ability to reject that protocol change. They might drive the price into the tank for awhile, but they've proven time and again that as long as they see they can continue to make money, they'll do so and so will end up just accepting it.

Full-nodes however, can reject those blocks, accept the 25% and bring about a split in the network etc.

But this is your error: non-mining full nodes don't have to reject or accept this. The miners themselves (the miner pool nodes) already did. The split was already there when the miner pools split. There were full MINING nodes broadcasting each of the chains, and these are the ONLY TWO SOURCES of the two chains that exist.

Let us call the, say, 6 pools that make the 75% "50 coins" chain, chain A and protocol A, and the 12 pools that make the 25% old protocol chain, chain B, and protocol B.

My statement is that indeed, all non-mining nodes might just as well be shut down, from the moment that the pools have sufficiently strong data center full nodes that everyone of us can connect to them directly.

Suppose now that you have an SPV wallet, and let us presume that the split doesn't affect the communication with the SPV wallet. If you connect your SPV wallet to one of the A-type pool nodes (MINING nodes), you will see your havings on that chain ; if you transact, you transact on that chain (let us presume that something is in place to avoid replay attacks, like a version number or something that alters the signatures). For instance, you can send them to an exchange that lists both coins, and sell them for LTC.However, if you connect your SPV wallet to the B-type pool nodes (MINING nodes), you will see your (initially identical) holdings on that chain. Your coins will still be there, even though you sold your A-type coins for litecoin.

Of course, if Joe, your neighbour, has a full node that he configures for protocol A, you can also use his node, that copies the chain from type-A pool nodes ; and if your other neighbour, Jack, has a full node that he configures for protocol B, you can use his node that copies the chain from type-B pool nodes. But they are just copies of the one or the other. If Joe and Jack aren't there, you can directly connect your SPV wallet to the sources of these data without using them as a proxy. And if you feel like it, you can run both nodes in your basement, and copy both block chains. But the only sources of chain A and chain B are the type-A mining nodes, and the type-B mining nodes. You can get copies if you want, or you can use copies from neighbours if they are around.

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Now the market has the ability to ultimately make the final decision. Yes, there will be chaos and the outcome would be unknown, but now it's in their hands.

So that means full nodes have zero power?

Yes, because the markets didn't need non-mining full nodes, as they could do it with the mining nodes that are the source of the data and are the processors of transactions in any case.

Now, this is an interesting market, because the miners of A have 4 times more coins than the miners of B for each block. So if the market would split into putting 4 times less value on coin A than on coin B, the miners would eventually switch to a 50%/50% hash rate split, because then, earnings per hash rate are in equilibrium again. In order for the 75% / 25% split to be maintained, coin A would have to have more than 1/2.3 the market value than coin B.

it doesn't increase the "security" of the system at all from being able to read a copy, if you can have the original.

What if I can't find someone to give me a copy ? The centralised miners could be coerced into wiping the old chain.. ( If I run a full node I never have to ask anyone for anything.. )

Then you will in any case not be able to transact anything, because no miner is around to accept your transaction. You cannot write yourself your transaction to the block chain you have on your own disk if you are a non-mining node. So if you cannot find ANY miner that has a running node, you cannot do anything with your block chain on your own node either, because NOBODY can add a block, including you.

Note that I did put a caveat of the catastrophe where all miner nodes were destroyed, bombed.... and that you are the one keeping the sole copy of the bitcoin block chain, then after 5 years you may indeed decide to restart bitcoin, if enough miners build again enough hash power to take up where it had been left.

If globally, ALL miners (you can't find a single one with the right block chain) have erased the old chain and make a new one, in any case, your old chain on your node is useless. You sync with them, and forget the old chain or you stop. You can only have transactions on a block chain that a miner is currently making.

As such, whatever you have on your own node, you'll have to adapt to what that miner is having on HIS node if you want him to write something to the chain HE's making.

Full nodes undertake a "UASF" and only accept blocks from the miners that are signaling for segwit and thus bring about a fork.

Well, then these nodes will stop if the block chain has a single block on it not signalling segwit. If you want to use that node, you cannot do any transactions any more. If you would start such node right now, it would simply stop at the first non-segwit signalling block. It would find that the next block (segwit signalling) is not one built on the last one that is valid according to him, and will never find any other block any more that suits him. So he stops. But the miners don't stop. They continue to make the chain like they make it today.

What's the difference between running such a stopped node left behind, and switching off the machine on which it runs ?

People (users) wanting to transact coins, will avoid your full node to connect their SPV wallet to, because your node is not at the current height. If all non-mining nodes do so, it is as if all of them switched off. So users will ultimately only connect to miner nodes. In a certain way, this looks somewhat like a sybil attack on the P2P network, by introducing a lot of nodes that have wrong data (stopped chains). But as we know, the P2P network doesn't mind Sybil attacks. Users wanting to transact will quickly blacklist them, to only connect to up-to-date nodes - ultimately, the miner pool data centers.

Suppose that an exchange installs such a node. Suddenly, its customers cannot withdraw any more or cannot deposit any more. I'm sure they are going to like it ! They will all run to an exchange that keeps accepting withdrawals and deposits. They will convert all their holdings on the former exchange to LTC, ripple or ETH, withdraw, and deposit on the exchange that keeps allowing bitcoin transactions on the sole chain that exists. And never go back to the former exchange again. (*)

Note that nobody can "vote in the market" as long as there is a single block chain, because you only have wallets that work, and wallets that don't work. Users, and exchanges, will prefer wallets that work.

(*) come to think of it, an exchange might very well do this temporarily, to make its customers sell their BTC they cannot withdraw for cheap, to switch back to a normal node afterwards, and reap in the difference !

Full nodes undertake a "UASF" and only accept blocks from the miners that are signaling for segwit and thus bring about a fork.

Well, then these nodes will stop if the block chain has a single block on it not signalling segwit.

That's based on the assumption that at least some of the miners that are currently signaling for segwit would not "switch" (at some point at least) to build the "segwit" blockchain. I hate using phrases like "their best economic interest" as most take short term gains and sacrifice or risk long term what's best for their economic interests. But in this case there would be some that see it as being in their best economic interest to join in the "UASF".